Poza de la Sal saltworks, Poza de la Sal, Burgos, Castile and Leon, Spaini

Regional Level Types
Poza de la Sal saltworks	Workings (Abandoned)
Poza de la Sal	Municipality
Burgos	Province
Castile and Leon	Autonomous Community
Spain	Country

The saltworks of Poza de la Sal are an old salt mining operation located in the municipality to which they give their name. They are located in a depression on the eastern edge of the moorland of Masa. The depression is formed by a sharp drop in the terrain from the 1,100 m above sea level of the moorland, to the 650 m above sea level of the plain of La Bureba.

The edges of the basin resemble a large crater almost 3 km in diameter that forms a very characteristic diapir. The origin of the formation of this structure dates back to approximately 240 million years ago, in the last phase of the Triassic and the sedimentation of the Keuper. At that time, there was a large lake here, at the bottom of which the clays and gypsum that were carried by the rivers that flowed into it were deposited. The progressive drying up of the inland sea as a result of a progressively warmer and drier climate, caused an increase in the precipitated saline concentration, which came to create a layer of 400 or 500 m thick.​

While this was happening, the upwelling of magma begins to cover the facies of Keuper, while leaving between the gypsum, saline and clayey strata, light rocks or ophites>. This process lasts throughout the Jurassic and the Cretaceous, until more than 60 million years ago, so that these materials covered the first layer of Keuper. As this layer is denser than that of gypsum, clay and Keuper's salt, the salt begins to rise along with the ophites and lighter materials, by a process known as halokinesis. This upward movement caused the rupture of the Jurassic cover and the collapse of its material, which formed a basin of large proportions. This basin is today perfectly distinguishable from the surroundings of Poza de la Sal.

The process is completed with the formation of the Sierra de Cantabria and the Obarenes, from about 40 million years ago, with the elevation of the Masa moorland and the descent of La Bureba, until one million years ago.

The first data on human settlement in Poza are those offered by the discovery of the El Castellar site. It is located on an ophithic outcrop that rises abruptly, controlling access from La Bureba to the moorland, and vice versa, and in it are the remains of what was possibly an Autrigon settlement that was later Romanized. These remains consist of fragments of undecorated blackish pottery from the Iron Age, others of Celtiberian origin, and others of Terra sigillata Hispanic origin.​

It is during the Middle Ages when Poza becomes a salt centre of great importance, and in the 15th century the new castle and walls were built to defend Poza and its salt (the primitive castle was probably located in El Castellar). The Catholic Monarchs facilitate the transport of salt, and Philip II decrees the state monopoly of the salt trade. Already in the 17th century the "casa de la Administración de las Salinas" ("the house of the administration of the saltworks") was built, and in the 19th century, coinciding with the period in which mining reached its highest production, the salt warehouses of the Public Treasury were erected. The decline began with the development and improvement of coastal salt production systems in the 20th century.

The salt was obtained by dissolving the rock with fresh water that was taken to the excavated wells, then transporting the brine through galleries to settling ponds so that the water evaporated from the sun's heat. The salt thus extracted remained in these pools until the end of the summer, when it was stored in buildings set up for this purpose. The construction of wells, galleries, aqueducts, settling ponds and terraces has left its mark on the landscape of Poza, which can still be clearly seen today, decades after the cessation of exploitation. These structures are given precise names:

Caña ("reed"): vertical shaft excavated up to the salt vein.

Galería ("gallery"): tunnel dug into the rock through which fresh water flowed.

Fuente ("sources"): place where fresh water was collected, to be conducted with pine gutters to the cañas. Among them, the Cubo, the Canto, the Nava, and the Villa stand out.

Pozos de reserva de agua ("water reserve wells"): reservoir to have water in times of scarcity.

Pozo de salmuera ("brine pit"): dug to accumulate the brine produced in the cañas.

Era ("threshing floor"): pool where brine was exposed to sunshine and salt crystallized.

Choza ("Hut"): enclosure where salt was provisionally accumulated on the "threshing floor", until it was transported to the warehouse.

Chozón: structure that allowed the "threshing floors" to be kept horizontally.

Albañal ("Sewer"): Excavated trench to direct torrential waters.

Other Databases

Wikipedia:	https://es.wikipedia.org/wiki/Salinas_de_Poza_de_la_Sal
Wikidata ID:	Q17739856

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